Cant format or Fdisk old 15 gig IBM drive

this old 15 gig IBM drive is driving me crazy! when I try to format it I get the error “format not supported” – if I try and use SuperFdisk it says “no drives ready” – but the drive runs just fine, it has windows 95 on it. if I try to install windows 98 it says it needs a boot partition before it can install. I tried different jumper positions but no luck. in dos i can type C: and DIR and it shows whats on the drive. Anyone have any ideas? I want to format and load win 98